package com.atguigu.study.aspect;

import com.atguigu.study.annotations.MyRedisCache;
import jakarta.annotation.Resource;
import lombok.extern.slf4j.Slf4j;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.Signature;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Pointcut;
import org.aspectj.lang.reflect.MethodSignature;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.expression.Expression;
import org.springframework.expression.spel.standard.SpelExpressionParser;
import org.springframework.expression.spel.support.StandardEvaluationContext;
import org.springframework.stereotype.Component;

import java.lang.reflect.Method;
import java.lang.reflect.Parameter;

@Aspect
@Component
@Slf4j
public class MyRedisCacheAspect {
    @Resource
    private RedisTemplate redisTemplate;

    @Pointcut("@annotation(com.atguigu.study.annotations.MyRedisCache)")
    public void cachePointCut() {

    }
    @Around("cachePointCut()")
    public Object docache(ProceedingJoinPoint joinPoint) {
        Object result = null;

        try {
            //1 获得重载后的方法名
            MethodSignature signature = (MethodSignature) joinPoint.getSignature();
            Method method = signature.getMethod();

            //2 确定方法名后获得该方法上面配置的注解标签MyRedisCache
            MyRedisCache annotation = method.getAnnotation(MyRedisCache.class);
            //3 拿到了MyRedisCache这个注解标签，获得该注解上面配置的参数进行封装和调用
            String keyPrefix = annotation.keyPrefix();
            String matchValue = annotation.matchValue();
            //4 SpringEL 解析器
            SpelExpressionParser expressionParser = new SpelExpressionParser();
            Expression expression = expressionParser.parseExpression(matchValue);
            StandardEvaluationContext context = new StandardEvaluationContext();
            //5 使用反射获得方法里面的形参信息
            Object[] args = joinPoint.getArgs();
            Parameter[] parameters = method.getParameters();
            for (int i = 0; i < parameters.length; i++) {
                System.out.println("获得方法里参数名和值" + parameters[i].getName() + "\t" + args[i].toString());
                context.setVariable(parameters[i].getName(), args[i].toString());
            }
            //6 通过上述，拼接redis的最终key形式
            String key = keyPrefix + ":" + expression.getValue(context).toString();
            //7 先去redis里面查询看有没有
            result = redisTemplate.opsForValue().get(key);
            if (result != null) {
                System.out.println("redis里有数据，直接返回");
                return result;
            } else {
                //8 redis里面没有，去找msyql查询或叫进行后续业务逻辑
                result = joinPoint.proceed();
                //9 mysql步骤结束，还需要把结果存入redis一次，缓存补偿
                if (result != null) {
                    System.out.println("缓存补偿" + result);
                    redisTemplate.opsForValue().set(key, result);
                }
            }
        } catch (Throwable e) {
            e.printStackTrace();
        }
        return result;
    }
}
